BOISE—The Idaho Department of Water Resources and state irrigation companies injected 75,239 acre-feet of surface water into the Eastern Snake Plain Aquifer during their first experiment with winter recharge, according to an end-of-season report.
IDWR Planning Bureau Chief Brian Patton said the program also helped the department identify policy changes and infrastructure improvements necessary to significantly expand the state’s recharge potential for future winters.
Recharge involves paying canal companies to let surface water seep through their unlined systems, or through injection wells or basins, to stabilize groundwater levels that have been declining by roughly 200,000 acre-feet per year since the 1950s.
This winter’s total includes 14,170 acre-feet recharged in the upper valley by Aberdeen-Springfield Canal Co., Great Feeder Canal Co. and Fremont-Madison Irrigation District. In the lower valley, Northside Canal Co., American Falls Reservoir District No. 2, Southwest Irrigation District and Twin Falls Canal Co. recharged 61,069 acre-feet.
“Hands down, the best point that came out of this past winter was the fact that theses canals were able to keep recharge flowing every single day,” Patton said. “I thought there would be shutdowns during extremely cold weather.”
Patton said canal managers implemented creative solutions, such as using pumps to recirculate water stop headgates from freezing.
Recharge was shut down March 5 in the upper valley, where canal companies made use of flood control water released from Palisades Reservoir, and it ended March 24 in the lower system due to the early start of the irrigation season.
Patton said the state recharged 84 percent of available water in the upper valley, despite losing four days of recharge while waiting for the Bureau of Reclamation to grant permission for canal companies to divert water prior to the start of the irrigation season. Patton said upper valley recharge is possible in about 50 percent of years, when water is released from reservoirs to clear space for flood control, and IDWR will prioritize finding a way to hasten the approval process for willing upper valley canal companies.
In the lower valley, where recharge is possible every winter, using water that passes below Milner Dam and can’t be put to other beneficial use, Patton said 19 percent of available water was recharged. But more than 300,000 acre-feet of available water spilled below Milner.
The top infrastructure priority entails improving a 3-mile section of concrete-lined canal on AFRD No. 2’s Milner-Gooding system, thereby opening up the Shoshone Basin recharge site for winter operations. An engineering company is also evaluating how to open more of Northside Canal Co.’s system to recharge. The company now has concerns about winter water freezing three hydropower turbines.
Brian Olmstead, manager of Twin Falls Canal Co., was impressed by the Idaho Water Resource Board’s commitment to working with canal companies to make the program a success.
“We need to do a lot more, but it was a real step in the right direction,” Olmstead said
Lynn Tominaga, executive director of Idaho Ground Water Appropriators, said temperatures dropped below zero during parts of November and December, and this winter’s efforts demonstrated recharge can occur even in bitter-cold weather.
Source: www.capitalpress.com